Structure of human teeth: a diagram and a description

This article is devoted to the study of the structure and functioning of the teeth - the vital organ of the human body. Teeth are a mirror image of human health, according to their unsatisfactory condition, it is possible to judge various functional disorders of the body. In addition, today a beautiful smile is the key to success in a career and in personal relationships. The structure of the article involves the coverage of a variety of issues, including the structure of human teeth; The scheme of their location in the dentition; Difference of infant teeth from permanent teeth; The need for proper dental care, etc.

Functions of the teeth

Teeth are bone formations in the oral cavity, which have a definite structure, shape, are characterized by the presence of their own nerve and blood vessel, lymphatic vessels, are arranged in the dental row and at the same time perform various functions. Teeth actively participate in breathing, as well as in the formation and pronunciation of sounds, the formation of speech. In addition, they perform primary mechanical processing of food, i.e., participate in one of the main functions of the vital functions of the organism - nutrition.

It should be noted that not enough chewed food is poorly digested and can cause disturbances in the work of the gastrointestinal tract. In addition, the absence of even a few teeth in the oral cavity affects the diction, i.e., the clarity of the pronunciation of the sounds. The aesthetic picture also deteriorates: facial features are distorted. Poor teeth can lead to bad breath, as well as the development of various diseases of the mouth and chronic infections of the body as a whole.

The structure of human teeth. Scheme of location in the jaw

The norm for a person is the presence of teeth in an amount of 28-32 units. By the age of 25, the dentition is usually complete. Teeth are located on both jaws, according to what distinguish the upper and lower dentition. The structure of the human jaw, teeth (their type classification) have the following form. Each of the rows contains 14-16 teeth. The series are symmetric and they are conventionally divided into the left and right sectors. Teeth are designated by ordinal numbers - two-digit numbers. The first figure is the sector of the upper or lower jaw, from 1 to 4.

During the closing of the jaws, the front teeth overlap the lower teeth by 1/3 of the crown of the tooth, and such a ratio of the dentition to each other is called a bite. If the teeth are not correctly closed, the bite is curved, which leads to a violation of the masticatory function, as well as to an aesthetic defect.

So-called wisdom teeth may be absent and, in principle, do not appear in the oral cavity. Today there is an opinion that this is a normal situation and the presence of these teeth is not necessary. Although this version causes a lot of contradictions.

Teeth can not recover. Their replacement occurs once during a person's life: first the baby has dairy teeth, then at the age of 6-8 years they change to permanent. Usually, by the age of 11, there is a complete replacement of the milk teeth with permanent teeth.

The structure of the tooth. Anatomy

The anatomical structure of the human tooth suggests that it consists of three parts: the crown of the tooth, the neck and the root.

The crown of the tooth is its part rising above the gum. The crown is covered with enamel - a strong tissue that protects the tooth from the damaging effects of bacteria and acids.

There are several types of dental crown surfaces:

• Occlusion - the surface at the point of closure with a pair of teeth on the opposite jaw.
• Facial (vestibular) - the surface of the tooth from the side of the cheek or lip.
• Lingual (lingual) - the inner surface of the tooth, inwardly directed into the oral cavity, ie, the surface with which the tongue touches when pronouncing sounds.
• Contact (approximate) - the surface of the dental crown, facing the teeth, located in the neighborhood.

The neck is the part of the tooth between the crown and the root that connects them, covered with gum edges and covered with cement. The neck has a narrowed shape.

The root is the part of the tooth with which it is attached to the dental hole. Depending on the classification type of the tooth, the root can have from one to several branches. More details will be considered below.

Histological structure

The histology of each tooth is exactly the same, however, each of them has a different shape in accordance with the function it performs. The drawing demonstrates quite clearly the layered structure of human teeth. The photo shows all dental tissues, as well as the location of the blood and lymph vessels.

The tooth is covered with enamel. It is the most durable fabric, consisting of 95% of mineral salts, such as magnesium, zinc, strontium, copper, iron, fluorine. The remaining 5% are organic substances - proteins, lipids, carbohydrates. In addition, the enamel includes a liquid that participates in physiological processes.

Enamel, in turn, also has an outer shell - the cuticle, which covers the chewing surface of the tooth, however, over time it has the property to thin out and wear off.

The basis of the tooth is dentin - bone tissue - a set of minerals, strong, surrounding the cavity of the entire tooth and the root canal. Dentin tissue includes a huge number of microscopic channels, through which exchange processes occur in the teeth. Nerve impulses are transmitted along the channels. For reference, 1 square. Mm dentin contains up to 75,000 tubules.

Pulp. Periodontium. The structure of the root

The internal cavity of the tooth forms a pulp - a soft tissue, loose in structure, thoroughly permeated with blood and lymphatic vessels, as well as nerve endings.

The structure of the roots of a person's teeth looks like this. The root of the tooth is located in the bone tissue of the jaw, in a special hole - the alveolus. The root, as well as the tooth crown, consists of a mineralized tissue - dentin, which is covered from the outside with cement - a cloth that is less durable than enamel. The dental root ends with the apex, through the hole in which the blood vessels that feed the tooth pass. The number of roots in the tooth varies according to its functional purpose, from one root in the incisors, to 4-5 roots in the chewing teeth.

Periodontitis is a connective tissue that fills the gap between the tooth root and the jaw socket in which it is located. The fibers of the fabric are weaved into the cement of the root on one side, and into the bone tissue of the jaw with the other, so that the tooth is secured firmly. In addition, through the tissues of the periodontal, the nutrients of the blood vessels enter the tissues of the tooth.

Types of teeth. Incisors

The human teeth are divided into four main groups:

• Incisors (central and lateral);
• Fangs;
• Premolars (small chewing / molars);
• Molars (large chewing / molars).

The human jaw has a symmetrical structure and includes the same number of teeth from each group. However, there are some anatomical features in such a matter as the structure of the teeth of the upper jaw and the teeth of the lower row. Let us consider them in more detail.

The front teeth are called incisors. A person has 8 such teeth - 4 on top and 4 from below. The incisors are designed to bite the food, divide it into pieces. A special structure of the human anterior teeth is that the incisors have a flat crown, in the form of a chisel, with rather sharp edges. On the slices anatomically three tubercles protrude, which during life have a property to wear off. On the upper jaw, two central incisors are the largest of all representatives of their group. The lateral incisors are similar in structure to the central incisors, however, they are smaller. Interestingly, the incisal edge of the lateral incisor also has three tubercles, and often assumes a convex shape due to the development of the central (middle) hillock. The root of the cutter is single, flat and takes the form of a cone. A characteristic feature of the tooth - from the side of the tooth cavity there are three tops of the pulp, which correspond to the bumps of the cutting edge.

The structure of the upper teeth of a man differs slightly from the anatomy of the teeth of the lower row, that is, on the lower jaw everything is exactly the opposite. The central incisors are smaller in comparison with the lateral ones, they have a thin root, shorter than that of the lateral incisors. The face of the tooth is slightly convex, but the lingual surface is concave.

Crown of lateral incisor very narrow and curved to lips. The cutting edge of the tooth has two corners - the central one, the more acute, and the lateral - the more blunt. The root is characterized by longitudinal grooves.

Fangs. Chewing teeth

Fangs are designed to divide food into smaller pieces. Anatomy of the tooth is such that on the rear (lingual) side of the crown passes a furrow, which disproportionately divides the crown into two parts. The cutting edge of the tooth has one developed pronounced tubercle, which makes the shape of the crown conical, often similar to the fangs of predatory animals.

The canine of the lower jaw has a narrower shape, the crown faces converge in the medial tubercle. The root of the tooth is flat, the longest in comparison with the roots of all other teeth and is rejected inward. A man has two canines on each jaw, one on each side.

Fangs together with lateral incisors form an arc, in the corner of which begins the transition from cutting teeth to chewing teeth.

Let's consider more carefully the structure of the human molar, first - a small chewing, then a large chewing. The main purpose of chewing teeth is careful mechanical processing of food. This function is performed by premolars and molars.

Premolary

The first premolar (denoted by the numeral 4 in the dental formula) differs from the canine and incisors in its prismatic form, the crown has convex surfaces. The chewing surface is characterized by the presence of two tubercles - buccal and lingual, furrows between the tubercles. The calcaneal tubercle is much more linguistic in size. The root of the first premolar is still flat, but it already has a split into the buccal and lingual part.

The second premolar is similar in shape to the first, however, its buccal surface is much larger, and the root has a conical shape, compressed in the anteroposterior direction.

The chewing surface of the first lower premolar is oblique toward the tongue. Crown of the tooth is round, the root is single, flat, with furrows on the frontal surface.

The second premolar is larger than the first, due to the fact that both hillocks are equally developed and symmetrical, and the depressions in the enamel (fissure) between them take the form of a horseshoe. The root of the tooth is similar to the root of the first premolar.

In the dental line of the person there are 8 premolars, 4 on each side (on the upper and lower jaws). Consider the anatomical features and, in general, the structure of the teeth of the upper jaw (large chewing teeth) and their differences from the structure of the teeth of the lower jaw.

Molars

The first molar of the upper jaw is the largest tooth. It is called a large molar tooth. The crown resembles a rectangle, and the chewing surface is a shape of a rhombus with four tubercles, between which the fissure of the H-shaped species is distinguishable. This tooth is characterized by three roots: one straight - the most powerful, and two cheek - flat, which are rejected in the anteroposterior direction. These teeth, when the jaws are closed, abut each other and are peculiar "restraints", and in this connection they undergo enormous loads during the life of a person.

The second molar is smaller than the first. The crown has a cubic shape with an X-shaped fissure between the tubercles. The roots of the tooth are similar to the roots of the first molar.

The structure of human teeth (the scheme of the location of molars and their number) completely coincides with the location of the previously described premolars.

The first molar of the lower jaw has five tubercles for chewing food - three buccal and two lingual with a L-shaped fissure between them. The tooth has two roots - a posterior one with one channel and anterior one - with two roots. In addition, the anterior root is longer than the posterior root.

The second molar of the lower jaw is similar to the first molar. The number of molars in a person coincides with the number of premolars.

The structure of human wisdom tooth. Baby teeth

The third molar in the people is called the "wisdom tooth", and in the human dentition there are only 4 such teeth, 2 on each jaw. On the lower jaw, the third molar can have many variants of development of tubercles. Often there are five. And in general, the anatomical structure of the human "wisdom tooth" is similar to the structure of the second molar, however, the root most often resembles a short and very powerful trunk.

As noted earlier, first a person has baby teeth. They usually grow to 2.5-3 years. The number of temporary teeth is 20. The anatomical and histological structure of a human milk tooth is similar to that of a permanent tooth, but there are some differences:

1. The size of the crown of the baby teeth is much smaller in comparison with the permanent ones.
2. The enamel of the baby teeth is more delicate, and the dentin composition has a lower degree of mineralization compared to the molars, so children often develop caries.
3. The volume of the pulp and the root canal of the milk tooth is much larger in comparison with the volume of the permanent tooth, because of what it is more susceptible to the occurrence of various inflammatory processes.
4. The tubercles on the masticatory and cutting surfaces are weakly expressed.
5. The incisors of the baby teeth are more prominent.
6. The roots are bent towards the lips, they are not so long and strong in comparison with the roots of permanent teeth. In this regard, the replacement of teeth in childhood - almost painless process.

In conclusion, I would like to note that, of course, the structure of a person's teeth, the scheme of their location in the jaw, and the closure (bite) have individual characteristics characteristic of each individual personality. However, the dental jaw apparatus of any person is involved in the performance of vital body functions throughout life, according to this, the structure of the teeth and their structure change over time. It should be remembered that most of the pathological processes in dentistry develop in childhood, so it is important to monitor the condition of the teeth from the first years of life. This will help to avoid problems with teeth at a conscious age.

Despite the apparent simplicity, the teeth are a very complex and fragile system, with a multilayered histological structure, each of the layers has an individual purpose and possesses certain properties. And the fact that the change of teeth occurs during life only once, makes the structure of the jaw of the person (teeth, their number) different from the anatomy of the jaw of representatives of the fauna.